In recent years, in an image forming apparatus of an electrophotographic type, the image forming apparatus for outputting the image by using the color toner and the transparent toner has been put into practical use. The transparent toner is a toner in which a colorant (pigment) is not contained, and cam adjusts glossiness without changing a color tint when being fixed on a recording material. Therefore, a constitution of the image forming apparatus in which the transparent toner is formed at a portion where the color toner is not formed to uniformize the glossiness of the whole image fixed on the recording material is disclosed in the following document.
In Japanese Laid-Open Patent Application (JP-A) 2008-65123, the image forming apparatus in which an image forming portion for clear (transparent) is disposed at a downstream side of image forming portions for yellow, magenta, cyan and black which are disposed along an intermediary transfer belt is shown. In the image forming apparatus described in JP-A 2008-65123, the four color developing devices using color toner developers and the transparent developing device using a transparent toner developer has just the same constitution.
Also in the image forming apparatus shown in JP-A 2008-176316, the four color developing devices and the transparent developing device which are disposed along the intermediary transfer belt are equally constituted. However, between the color developing devices and the transparent developing device, rotational directions of developer carrying members rotating around fixed magnets are set at opposite directions.
Also in the image forming apparatus shown in JP-A 2007-199209, four color developing devices using color toner two-component developers and a transparent developing device using a transparent toner two-component developer is disclosed. Further, constitutions of the color developing devices and a constitution of the transparent developing device are equal to each other.
Here, in the case where a glossiness of the image is intended to be uniform by using the transparent toner, an amount of use of the color toners. When the toner in the developing device is consumed by development, an uncharged (or small charge amount) toner is supplied into the developing device so as to compensate for a consumption amount (component).
That is, compared with the color toner, the amount of the transparent toner supplied into the developing device which accommodates the transparent toner becomes large. When the amount of the toner supplied into the developing device becomes large, the amount of the toner, fed to the neighborhood of a developing sleeve as a developer carrying member, which has a small charge amount per unit weight (or which is unchanged) without being sufficiently stirred (charged) becomes large.
Such a problem that the toner with the small charge amount is carried on the developing sleeve as the developer carrying member and is deposited on a non-image portion when it reaches a developing region where the electrostatic image carried on the photosensitive member is developed occurs. There was also a problem such that the toner with the small charge amount is scattered without being subjected to the development of the electrostatic image.
Therefore, an object of the present invention is to bring the charge amount per unit weight of the transparent toner close to the charge amount per unit weight of the color toner. Specifically, the object is to suppress scattering of the transparent toner caused by an increase in amount of use of the transparent toner compared with the color toner and by conveyance of the toner, with a charge amount smaller than a desired charge amount, to the neighborhood of the developing sleeve.